Micro-LED Transfer via Laser Lift-Off Mask
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Solution Overview
Problem
The existing methods for transferring micro-LEDs from a donor wafer to a receiving substrate are complex and costly, requiring multiple transfers and imposing thermal limitations that can degrade micro-LED performance, particularly due to the need for a complicated pick-up head system and temporary bonding with intermediate carrier substrates.
Innovation Solution
A method involving the formation of a mask layer on a laser-transparent original substrate, where micro-LEDs are lifted off using an electromagnetic force applied through a laser irradiation process, allowing direct and efficient transfer to a receiving substrate with reduced thermal stress and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic pick-up with transfer head array is used, then micro-LED transfer can be achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention extracts and eliminates the complex transfer head array system from the micro-LED transfer process. Instead of using an electrostatic pick-up system with transfer heads, the patent employs a straightforward laser lift-off method where the laser beam directly acts on the micro-LEDs on the donor wafer to release them onto the receiving substrate, thereby removing the intermediary complex equipment.
Solution Approach 2:
The invention replaces the mechanical/electrostatic transfer head array system with an optical field-based laser lift-off system. The laser beam creates a localized thermal field that selectively releases micro-LEDs without requiring physical contact or complex mechanical positioning systems, thus substituting a simple optical system for a complex mechanical one.
2Reliability
If phase change method is used for transfer, then micro-LED transfer can be achieved, but thermal budget is limited below 350°C which degrades micro-LED performance
Solution Approach 1:
The invention applies local quality by concentrating the laser energy into a focused beam that creates a localized thermal field only at the specific location where micro-LED release is needed. This localized heating allows the process to overcome the thermal budget limitation by confining high temperature effects to a small region, preventing overall thermal degradation of the micro-LEDs while achieving effective release.
3Reliability
If two transfers are performed (donor wafer to carrier wafer, then carrier wafer to receiving substrate), then micro-LED transfer can be achieved, but manufacturing time and complexity increase
Solution Approach 1:
The invention merges the transfer process into a single direct operation from the donor wafer to the receiving substrate. By eliminating the intermediate carrier wafer step and using the laser lift-off method, the patent combines what was previously two separate transfer operations into one integrated process, thereby reducing manufacturing cycle time and simplifying the overall workflow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the transfer process, reduces costs, and maintains high micro-LED quality by eliminating the need for multiple transfers and complex pick-up systems, while allowing for efficient and reliable manufacturing with improved throughput and performance.
Implementation Method 1
irradiating the original substrate from the original substrate side with laser through the mask layer
Implementation Method 2
a contactless action is applied onto the micro-LEDs, and the contactless action is electromagnetic force
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D~2F
AI summary
A transferring method, a manufacturing method, a device and an electronics apparatus of micro-LED. The method for transferring micro-LEDs comprises: forming a mask layer on the backside of a laser-transparent original substrate, wherein micro-LEDs are formed on the front-side of the original substrate (s4100); bringing the micro-LEDs on the original substrate in contact with preset pads on a receiving substrate (s4200); and irradiating the original substrate from the original substrate side with laser through the mask layer, to lift-off micro-LEDs from the original substrate (s4300).